The present invention relates generrally to a portable guide arrangement for facilitating the cutting of mitered joints with a portable power saw.
Portable power saws of the simpler saw type, commonly known as builder saws, are in widespread use in the construction industry and have, to a large extent, supplanted the large amount of hand sawing formerly required in the building trade. Such saws are particularly well-suited for the numerous cross-cuts necessary in the rough framing of buildings and for such work, may be readily hand guided to produce satisfactory cuts. However, for finish work, such as the interior or exterior trim and, especially for miter joints which must be accurately executed, the portable saw has proven difficult to control without some type of auxilary guide. The difficulty stems primarily from the problem of aligning the circular saw blade, which is practically concealed in a cumbersome casing and guard. In addition, the vibration and high cutting speed of the saw and, the line obscuring saw dust, generated during a cut, impede accurate work. Since it cannot be usually determined until well after a cut is started whether the saw is, in fact, properly aligned with the desired cut line false starts are common in hand guided saw operations and a considerable wastage of material and time results.
Because of the above difficulties, incidental to hand guided saw operations, guide arrangements of various types have been devised for portable power saws to permit a correct initial alignment of the saw and to maintain the alignment during the cutting operation. The miter guides, previously developed, generally include a horizontal track for guiding the saw over the work piece to be cut and the guide in normally pivotally mounted on a work supporting table to permit adjustment to the desired cutting angle. Such guides have the further advantage of permitting multiple cuts at the same cutting angle with a substantial savings of time and an improved accuracy over the former cutting methods.
A serious short coming of such devices has been the cumbersome nature of the table saw which must be carried to the work station and set up each time. An example of such guides in combination with a tabe are shown in U.S. Pat. No. 2,803,271.
Still another approach has been found in U.S. Pat. No. 2,714,903. The device of this patent has a base mechanism which clamps onto the work table and has two lateral guides for extending across the work piece. This device also requires a work table to support the base of the saw guide.
A similar saw guide is found in U.S. Pat No. 2,630,146, wherein the saw guides and support are pivotally supported on a base which is clamped to a work table. Again this necessitates the use of a permanent clamping mechanism to clamp it to a table. Similar saw guides are found in U. S. Pat. Nos. 2,513,497 and 3,368,594.